News from Clinical Research Office of the Endourological Society (CROES)

Ureteroscopy (URS) is nowadays at the core of endourology, and continuous updating on the matter is a cornerstone for every urologist. The clinical research office of the Endourological Society (CROES) has conformed a global, multicentric study group, which is deeply involved in such updating. Indeed, a URS Global Study was established to provide a prospective global database on ureteroscopic stone treatment.

Between January 2010 and October 2012, 11,885 patients received URS at 114 centers in 32 countries. Different variables concerning indication for URS, equipment used, patient outcomes, and specific factors connected to treatment-related morbidity ¹ were analyzed. This database rendered relevant publications that deserve our attention.

Overall results of the URS study revealed quite homogeneous stone-free rates (SFRs), with a mean of 85.2% in all centers. Also, 89.2% of patients did not require retreatment. Complications during surgery were rare (1.4%) and 3.5% of patients had post operatory complications according to the modified Clavien classification. ¹

Interestingly, patients with stone formation risk factors had significantly more complications. Also, the patient group with anticoagulant use had the highest risk of complications, namely 7%. ²

Two substantial controversies of everyday endourology were addressed by the study: the use of Double-J stents and ureteral access sheaths (UASs). On the one hand, 82.6% of patients received Double-J stents after URS. Patients with distal ureteral stones were least likely to have a stent placed. Also, the matter of pre-URS stenting was studied. It was found that the use of a Double-J stent in ureteric stone treatment did not result in higher SFRs or lower complications. For renal stones, preoperative stenting increased SFR and decreased intraoperative complications. ³ Second, regarding UAS use, a total of 2239 patients with renal stones were treated with flexible URS. Most patients (67%) were treated with the use of an UAS. After adjusting for possible confounders, no significant differences were found in SFR when an UAS was used or not. Remarkably, intraoperative complication rates were favorable for the UAS group, including less ureteral damage or bleeding. Also, less infectious complications were found in the UAS group. ⁴

It is well known that infections are an important complication after URS. This was also addressed by the study, in which 1.8% patients had postoperatory fever, 1% had urinary tract infections (UTIs), and 0.3% had sepsis after URS. A matched case–control analysis was done between patients who did and did not receive antibiotic profilaxis during URS. The conclusion was that the prevalence of postoperative fever or UTI in patients with a baseline negative urine culture undergoing ureteral or kidney stone removal was low and unaffected by antibiotic prophylaxis. We must point out that 82% received antibiotic profilaxis and 73.8% were discharged with antibiotics. Also, females and patients with higher ASA score were more likely to present fever or UTI as a complication. ⁵

Stone location was another issue highlighted in this study: analysis revealed that SFR was highest for distal stones and lowest for patients with multiple stone locations. These patients also had the highest risk of complications and highest retreatment risk. Also, despite the fact that there was no significant difference in overall SFR when comparing flexible URS versus semirigid URS, the former had significantly fewer treatment failures or retreatments in patients with proximal or multiple stones. ⁶

Single renal stones treated with flexible URS were analyzed as well. It was concluded that the threshold for low-complication, high-SFR retrograde intrarenal surgery (RIRS) should be 15 mm. Larger stones are feasible with RIRS, but surgeon experience and case volume are key factors, as well as the need to inform the patient about the higher risk of complications and need for retreatment. ⁷

Finally, case volume was considered: based on study results, high-volume centers were defined as those that performed more than 65 URSs per year. It was found that high-volume centers achieved higher SFR with few complications, shorter hospital stay, and fewer patients requiring retreatment or readmission than low-volume centers. Also, outcome measures improved with an increase in case volume. ⁸

URS experience is growing in all places. Though techniques and indications may differ according to each center, global outcomes show that URS has become a safe and effective strategy for treating both ureteral and renal stones. The CROES URS study has addressed core issues of stone treatment, as a result of meaningful participation from all over the world. All those willing to contribute on CROES registries are welcome to become involved, as it enriches both personal and global insight.